1. Field of the Invention
The invention is directed to a contact for use in terminating fine wire with varnish-type insulation. In particular, the invention is directed to a contact which is reliable in various environments.
2. Brief Description of the Prior Art
It is known in the industry to use contact terminals to terminate coils. The contact terminals do not require soldering but rather penetrate the insulation of the coil wire and establish electrical contact with the core thereof. U.S. Pat. Nos. 4,026,013 and 3,979,615 show two types of contact terminals which are being used in the electrical industry for establishing contact with electrical coils. In accordance with the principles of these prior art patents, cavities are provided in the coil support which are dimensioned to receive the terminals and the coil wire is located in these cavities during the winding process. After the winding process has been completed, it is merely necessary to insert terminals into the cavities to establish contact with the ends of the wire. The above identified patents do not required separate terminal posts on the bobbin.
It is also known in the industry to provide a bobbin which has wire binding posts extending therefrom as part of the bobbin molding, as shown in U.S. Pat. No. 4,166,265. The coil bobbin has terminal receiving cavities in one of its flanges which are located such that the operations of wrapping the coil wire around the first binding post, passing the coil wire through one of the cavities, winding the required number of turns on the coil supporting surface, passing the wire through the second cavity and finally wrapping the wire around the remaining post, can be carried out by a coil winding machine. After these operations have been carried out, terminals can be inserted into the cavities and the binding posts can be cut from the bobbin. Cutting of the binding post also results in cutting the coil wire adjacent to the fixed ends of the binding posts. The completed bobbin thus contains terminals in its terminal receiving cavities which are connected to the coil wire and which can be connected to the external conductors when the coil is placed in a circuit.
Although the termination described in U.S. Pat. No. 4,166,265 provides for a reliable electrical connection is certain instances, in other instances the electrical connection may fail as the coil wire is not adequately retained in position relative to the contact terminal. The coil wire is trapped between the housing and the contact terminal inserted therein. As the connector is exposed to various environments, the housing and terminals are caused to expand or contract. As the housing and terminals are made from different materials, the rate of expansion and contraction will vary between the materials. Consequently, in various environments the housing will be moved away from the terminal, allowing the coil wire to move relative to the contact terminal. The result is the loss of the electrical connection between the terminal and the wire, as the coil wire is moved out of electrical contact with the contact terminal. This is an unacceptable result.